Gfx card, monitor or video cable error?

I just installed a Gainward ATI Radeaon HD 4870 1GB GS. Performance is great with acceptable temperatures. However, I occasionally get green pixels popping up on my screen. Sometimes, some buttons or frames get discolored (weird static or digital scratches). These pixels and discolorations stick to the object it appears on (ie. if you move the object, the pixels follow suit). The same happens on both normal and Turbo (overclock) mode.

Previously, I was running on a Leadtek 8600GT with no such problem. I'm still using the same monitor, a Dell 2407WFP. I'm using a standard DVI cable (the version with missing pins). My discoloration/green pixel problem did not happen when I connected to my 4870 using an analog VGA cable (DVI input looks better though).

I ran ATITools 0.27 and initiated a Scan for Artifacts. I get yellow pixels appearing on the 3D screen and the message "Delta of xxx in xx pixels (xxx avg). No errors for xx:xx:xx sec." Not sure what this means (has nothing to do with the monitor though as recorded print screens show the dots on other PCs).

Now I'm uncertain whether I've got a problem with my gfx card, monitor or video cable. I'm wondering if a full pin DVI cable might help. I'm running out of ideas to trouble-shoot and pin-point the problem's root cause.

My rig's remaining specs are:
E8400 CPU @ 3GHz
Asus P5Q Pro motherboard
2GB Kingston KVR667 DDR2 RAM
Cooler Master Centurion 590 chassis
Enermax FMAII 535W PSU

Anyone with some ideas to share? Help!!!

Turning up the fan doesn't help. The artifacts are still there. Furthermore, at full load, my GPU hovers less than 60 degrees C. I doubt it's the temperature.

I'm hoping to get the shop I bought it from to give me a 1-to-1 exchange with a new card. It's barely a week old.